MSB

Depending on context, either the most signifigant byte or most signifigant bit. For example, in a 32-bit word, the MSBit is equal to 1<<31 == 2^31 == 2147483748, whereas the MSByte is equal to i<<24 == i*(1<<24) == i*16777216, where i is the value of the byte; for example, if i==1, MSByte==16777216.

Contrast this to the LSB, which is always equivalent to 1 (whether it's the LSBit or LSByte).